The use of a two-phase liquid/gas stream to clean pipelines is disclosed in European Patent Application 0 490 117 A1 to Kuebler that was published on Jun. 17, 1992 as an alternative to conventional clean-in-place (CIP) techniques in order to reduce the amount of chemicals used. Kuebler describes cleaning pipelines using a two-phase liquid/gas stream and a reduction in throughput of the cleaning liquid by several orders of magnitude relative to conventional clean-in-place techniques.
Additional publications describing mixed phased flow include, for example, U.S. Pat. No. 6,326,340 to Labib et al.; U.S. Pat. No. 6,454,871 to Labib et al.; and U.S. Pat. No. 6,027,572 to Labib et al.